cpu/qemu-x86/Kconfig: Drop redundant selects

The `ARCH_POSTCAR_X86_32` and `ARCH_POSTCAR_X86_64` options are already
selected indirectly. There's no need to explicitly select them.

Change-Id: Iaa2e99e6f0765741fc5af67180d116bb6cc23d38
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55757
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/cpu/qemu-x86/Kconfig

@@ -51,12 +51,10 @@ config MAX_CPUS
 config CPU_QEMU_X86_64
 	bool "Experimental 64bit support"
 	select ARCH_ALL_STAGES_X86_64
-	select ARCH_POSTCAR_X86_64
 
 config CPU_QEMU_X86_32
 	bool
 	default n if CPU_QEMU_X86_64
 	default y
 	select ARCH_ALL_STAGES_X86_32
-	select ARCH_POSTCAR_X86_32
 endif